Many people feel tired during the day, sleepless at night, dizzy and even confused after traveling to a different time zone. Similar symptoms are caused by changing sleep schedules due to daylight saving time or changes to the work schedule.

A new study finds that oxygen could play a key role in resetting our biological clock after its adjustment with the environment is disrupted. According to a study published yesterday in the journal Cell Metabolism, lower — or higher — oxygen levels alleviate symptoms of jet lag in mice.

The study’s lead researcher, Dr. Gad Asher of the Weizmann Institute’s Biomolecular Sciences Department, says physiological reset is “a situation in which the body’s biological processes, even in each cell, are adjusted to the environment’s time tables.”

He compares it to a large audience, in which all the people’s watches are coordinated. “That’s about what happens to our body’s biological clock when we need to synchronize it,” Asher told Haaretz.

The circadian clocks in cells enable light-sensitive organisms to coordinate their biology and behavior with changes in the light-dark cycles. “This advanced internal clock was first described scientifically in the 18th century, but only in the last few years we’re beginning to understand its importance, especially in the context of metabolism and effect on quality of life,” says Asher.

Recent studies link obesity, diabetes and other metabolic diseases with disruptions in the circadian clock, in addition to studies of sleep disorders that find higher morbidity among night-shift workers. Other studies have found that light pollution contributes to the prevalence of certain diseases.

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Jet lag is merely a common manifestation of a chronological-biological disruption, whose frequency increases as our world becomes smaller and more saturated by artificial light.

Asher says today’s circadian clock research includes chronotherapy (the best time in the day to take certain medicines) and chrononutrition (when and what to eat according to the circadian clock).

The study’s research team included Asher’s Weizmann colleagues Yaarit Adamovich, Benjamin Ladeuix and Marina Golik.

“The circadian clock consists of millions of clocks in every limb and cell,” says Adamovich. “We wanted to understand what enables the coordination among them, what makes them ‘tick’ in harmony.”

Scientists knew that temperature and eating schedules affect the circadian clock. Since both processes involve a change in oxygen consumption, they studied whether it serves as a coordinating signal for the body’s clocks.

“Such a sign must be known to the body’s cells and must have a circadian rhythm. It must also affect all the cells and make them present the same time,” says Asher.

Oxygen is identified by most body cells and fulfils the first requirement. The scientists created a jet lag situation by altering the hours of light and darkness in the mice laboratory. “This made the mice skip six hours ahead in time,” says Adamovich. “Like a flight from Israel to a country in the Far East.”

One group of mice was exposed to lower oxygen levels for several hours, while another, which served as the control group, was exposed to a steady oxygen level. The mice in the first group suffered from jet lag for a significantly shorter period.

“We reduced the oxygen level in the air from 21 percent to 14 percent. It shortened their adjustment time from eight to five days,” says Asher. “We showed that oxygen can affect the body clocks’ coordination.”

Understanding how oxygen affects the circadian clock is relevant to more than jet lag, but also to people suffering from heart, vascular and chronic lung diseases, sleep disorders and more.

“We show that oxygen works for mammals, especially rodents, but it will be interesting to check whether it can regulate the clock for bacteria, plants, flies and other organisms,” says Asher.

“Now, for example, we’re checking if oxygen-rich air can also shorten recovery from jet lag. If the method is effective, we could think of simple solutions to implement it, for example, using oxygen masks in planes,” he says.

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